Stylus-Activated Pie Menus? Tablet Mode Sculpting?
You can map one of the pen or tablet buttons in Wacom Tablet Properties to Ctrl+Tab as per this list of Blender shortcuts. Note that you can create a specific setting just for Blender.

Go to Wacom Tablet Properties
Optionally, set a specific application
Select the dropdown menu for the button you plan on changing
Select &quot;Keystroke...&quot;
Press Ctrl+Tab, optionally name the shortcut key, and then click on OK

(click images to enlarge)